﻿using System;
using System.Drawing;
using System.Drawing.Imaging;
using System.IO;

namespace DTcms.Core.Common.Helper
{
    /// <summary>
    /// 验证码帮助类
    /// </summary>
    public class VerifyCodeHelper
    {
        private static readonly string Letters = "1,2,3,4,5,6,7,8,9,A,B,C,D,E,F,G,H,J,K,L,M,N,P,Q,R,S,T,U,V,W,X,Y,Z";
        /// <summary>
        /// 生成验证码图片
        /// </summary>
        public static MemoryStream Create(string captchaCode, int width = 0, int height = 30)
        {
            //验证码颜色集合
            Color[] c = { Color.Black, Color.Red, Color.DarkBlue, Color.Green, Color.Orange, Color.Brown, Color.DarkCyan, Color.Purple };
            //验证码字体集合
            string[] fonts = { "Verdana", "Microsoft Sans Serif", "Comic Sans MS", "Arial" };
            //验证码宽度
            if (width == 0) width = captchaCode.Length * 20;
            //定义图像的大小，生成图像的实例
            var image = new Bitmap(width, height);
            var g = Graphics.FromImage(image);
            //背景设为白色
            //g.Clear(Color.White);
            var random = new Random();
            for (var i = 0; i < 100; i++)
            {
                var x = random.Next(image.Width);
                var y = random.Next(image.Height);
                g.DrawRectangle(new Pen(Color.LightGray, 0), x, y, 1, 1);
            }

            //验证码绘制在g中
            for (var i = 0; i < captchaCode.Length; i++)
            {
                //随机颜色索引值
                var cindex = random.Next(c.Length);
                //随机字体索引值
                var findex = random.Next(fonts.Length);
                //字体
                //var f = new Font(fonts[findex], 15, FontStyle.Bold);
                var f = new Font(fonts[findex], height / 2, FontStyle.Bold);
                //颜色  
                Brush b = new SolidBrush(c[cindex]);
                var y = 4;
                if ((i + 1) % 2 == 0) y = 2;
                //绘制一个验证字符  
                //g.DrawString(captchaCode.Substring(i, 1), f, b, 12 + (i * 12), ii);
                int w = width / (captchaCode.Length + 2);
                g.DrawString(captchaCode.Substring(i, 1), f, b, w + (w * i), y);
            }

            var ms = new MemoryStream();
            image.Save(ms, ImageFormat.Png);
            g.Dispose();
            image.Dispose();

            return ms;
        }

        /// <summary>
        /// 生成验证码随机数
        /// </summary>
        public static string RandomCode(int codeLength = 4)
        {
            var array = Letters.Split(new[] { ',' });
            var random = new Random();
            var temp = -1;
            var captcheCode = string.Empty;
            for (int i = 0; i < codeLength; i++)
            {
                if (temp != -1)
                    random = new Random(i * temp * unchecked((int)DateTime.Now.Ticks));
                var index = random.Next(array.Length);
                if (temp != -1 && temp == index)
                    return RandomCode(codeLength);
                temp = index;
                captcheCode += array[index];
            }
            return captcheCode;
        }
    }
}
